Toshimitsu Shigemura, a professor at Japan's Waseda University and an expert on North Korea, told The Telegraph North Korea feels is has a connection with the UK because "they see themselves as a sort of Korean royal family."

"North Korea is looking for new friends, while they have also sent officials to London to make money on the stock market and seek development aid," he said.

"But there is also real concern in the leadership there that the regime could collapse without China's support, so they are looking for a country that might provide them with political asylum. It is possible that they think Britain might provide that."

Japanese media recently reported that it had seen leaked copies of China's contingency plans for the collapse of North Korea - with some reports suggesting that it could soon be "all over" for Kim Jong-un's regime.

China is North Korea's most important diplomatic and economic ally, but three nuclear tests and several rounds of sabre rattling have tested Beijing's support.

In January, Beijing halted exports of critically important oil over the border, an unprecedented act that highlighted the level of frustration.